The Animal Surgery Core is designed to perform all the operative procedures as required for the testing of each of the overall group hypotheses and for each of the specific hypotheses in each of the three projects. It is staffed by the Project Director and the animal surgery technician. Objectives and functions of the Core are as follows: 1) to perform all of the animal operative procedures needed for the entire Project; 2) to monitor the health status of the operated rats; 3) to schedule experiments and operations; 4) to assist in tissue removal and distribution to the Project laboratories, and 5) to remove all control and operated muscle from rats when contractile properties are being determined. Operations to be performed are standard EDL, nerve-implant and nerve-intact EDL: grafts, and nerve transection and nerve grafting. The maintenance of the experimental animals, along with dealing with animal pathology, will be done by the Unit for Laboratory Animal Medicine (ULAM) at the University of Michigan.